We’re so used to being conned by everyone from the government to our smartphone providers, that a film purporting to tell it like it is, raises suspicions. But Citizenfour, while guilty of sins of omission, marshalls the hard truths and goes easy on the varnish. Laura Poitras completes her trilogy on post-9/11 America, begun with 2006’s My Country, My Country and 2010’s The Oath, with this potent and profound documentary that bears cinematic witness to history with the actual participants instead of the usual pontificating, proselytizing talking heads. Citizenfour is a wake-up call that hits you like a cold slap in the face.

Poitras’ subject is former NSA intelligence analyst Edward Snowden, the whistleblower who first made contact with Poitras under the codename “Citizenfour.” OK, we’ve read reams about Snowden. We think we know it all, from his former life in Hawaii to his refuge in Russia. We don’t. Citizenfour lets us see Snowden, then 29, meeting in 2013 with Poitras, journalist Glenn Greenwald and U.K. intelligence reporter Ewen MacAskill over eight days in a Hong Kong hotel room. Snowden, charged with violating the Espionage Act, owns up to his personal responsibility, and his fear and vulnerability are palpable. His argument, cogently expressed, is that the public has a moral right to the know the widespread extent to which the government, cloaked in the defense of monitoring global terrorism, is spying on its citizens, right down to each email and Google search. In news clips, we watch NSA reps lying through their teeth.

The film has a “You Are There” urgency that escalates in tension as the journalists help Snowden disseminate his stolen data to the world. In the final scene, in a Moscow hotel room, Greenwald gives Snowden evidence that there’s a new, higher-placed whistleblower in town, ready to expose America’s surge from democracy to surveillance state and ready to name names that extend as high as POTUS. Citizenfour leaves you reeling. That’s its intention. It’s a wow of a thriller with a soul that isn’t computer generated. Poitras may be guilty of taking Snowden at face value, but she succeeds brilliantly in evoking a shadow villain intent on world domination. Big Brother is back, baby, and he’s gone digital.